The purpose of this investigation is to identify the effect of single- dose disulfiram on human cytochrome P4502A6 activity in vivo, using coumarin 7-hydroxylation as the in vivo probe for human P4502A6. Our hypothesis is that disulfiram will have no effect on in vivo P4502A6 activity and we expect to find that coumarin clearance and 7-OH-coumarin formation clearance will not be significantly diminished by disulfiram.